Available evidence in the epidemiology of diabetes indicates that the phenotypic expression of the genetic determinants of the disease are modified by environmental conditions often associated with changes in diet. Although many investigators have explored a variety of dietary hypotheses, after standardizing for obesity and/or total caloric intake, the data remain unconvincing. If specific dietary nutrients that were independently associated with the onset of diabetes (particularly adult type) could be identified, then strategies to prevent expression of the disease might be developed. The proposed investigation to explore dietary risk factors for diabetes in women takes advantage of the ongoing prospective cohort study of 121,964 registered nurses ages 30-55 in 1976, who are followed every 2 years by mail questionnaire and appropriate follow-up to confirm diagnoses. Approximately 2000 prevalent cases of diabetes were originally reported in 1976, and since that time increasing numbers of newly diagnosed cases are being reported. By the end of the 1984 mailing cycle (8 years) approximately 2100 incident cases will have been reported with approximately 700 reported in the interval 1982-1984. Information on a number of risk factors for diabetes has been gathered since 1976 and a detailed food frequency questionnaire was obtained on the entire cohort in 1980. Thus, after controlling for family history of diabetes and obesity, the importance of several dietary risk factors for diabetes (simple sugars, complex carbohydrates, fats, fiber, and alcohol) can be assessed. In addition, in 1982-83 toenail specimens on approximately 65,000 members of the cohort are being collected and newly diagnosed diabetics in 1984 will be compared with appropriate matched controls for chromium levels, a reported risk factor for diabetes, along with zinc levels which we can obtain at little additional cost. The proposed study will document and classify the diagnosis among the women. Stratified and multivariate techniques will be used to quantitate the risk of onset of the disease and different levels of nutrient intake after controlling for other potentially important risk factors such as age, family history and obesity.